


a vigilant heart

by juryrouge



Category: Fullmetal Alchemist - All Media Types, Fullmetal Alchemist: Brotherhood & Manga
Genre: Amestris, Canon Universe, CathLan, F/F, First Meetings, Fluff, Light Angst, Post-Promised Day, Pre-Relationship, Promises, Slow Dancing
Language: English
Status: Completed
Published: 2020-07-27
Updated: 2021-01-21
Packaged: 2021-03-05 22:01:39
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 2
Words: 4,419
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25522531
Author URL: https://archiveofourown.org/users/juryrouge/pseuds/juryrouge
Summary: The air was thick with the sweetness of early springtime, the balcony overlooking Central City was startlingly quiet, and Catherine and Lan Fan met under the stars.
Relationships: Catherine Elle Armstrong & Olivier Mira Armstrong, Catherine Elle Armstrong/Lan Fan, Lan Fan & Ling Yao
Comments: 42
Kudos: 26





	1. tracing the stars

**Author's Note:**

> here is some cathlan because i am soft and i want to contribute to the pairing. thank you so much to arianeige- you are absolutely amazing. please enjoy the start of this new series. and please enjoy the fic!
> 
> -jury

It all came down to politics, really. Ling had become the Emperor of Xing, a title that Lan Fan knew he was always destined to carry, and with that, unfortunately, came court politics. Even worse, in Lan Fan’s opinion, international politics. At least in the royal palace, there were trained and dedicated guards in every corner of every room, all working under her orders; traveling to foreign soil, however, was just begging for assassination attempts. 

This was why Lan Fan had a vast amount of work to get done in preparation for Ling’s diplomatic mission to Amestris. 

Lan Fan remembered the last time she and her prince had made this journey. The desert heat, scorching with the flames of a red sun, had been unforgiving, the air dried with dust. Each step she took was painful, sand clawing up her legs, threatening to sink her if she rested for even a moment -- until Ling demanded they stop at Xerxes. 

The ruins of a desolate civilization stared at them, its ancient murals looming over them as they passed between half-broken statues. There were depictions of raging lions and sunken moons and men with alluring golden eyes. 

And when they reached Amestris, they had one goal in mind: immortality.

Their most recent journey couldn’t have been more different. The sand of the desert stormed with unrelenting power, the harsh winds singing a sweet melody of peril that weaker men would have fallen to. But Ling and Lan Fan didn’t have to worry about that; worrying about such frivolities like _brutal weather_ was a job for the emperor’s advisors and the workers escorting them to Amestris. All Ling had to decide was whether he wanted to stop at Xerxes again or take another food break.

And their welcome at Amestris couldn’t have been more luxurious. Fuhrer Grumman had placed them in the best hotel money could buy and after Lan Fan had secured the building, Ling made quick haste for the restaurant attached -- she made sure to check the food too. 

“I should make favor with Grumman,” Ling mentioned, hardly stopping to breathe between bites. “But more importantly, I heard that Roy Mustang will succeed him soon; that will make my life a lot easier. Oh, the Armstrong siblings should be there as well.” The Amestrian government was hosting a ball before many of the proceeding diplomatic talks, of which many foreign ambassadors and leaders would be in attendance. 

“I heard Edward will be there as a translator. Don’t get into too much trouble with him.”

Ling almost choked on the food he was eating. He put his hand up before Lan Fan could overreact and drank a glass of water. “What are you? My advisor? I know how to keep myself out of trouble.”

She nodded slowly. “Will you talk to him?”

“Of course I would want to catch up with my friend,” Ling responded, an awkward edge to his tone. He sounded like a scolded child. “But I know how to properly conduct myself.”

“Of course, Emperor Ling.”

After a good night’s rest and a day of preparation, the ball was upon them. Lan Fan wore a black suit, crafted in the most modern Amestrian style, specially stitched to host a variety of her weapons. Ling wore the traditional robes of an emperor, a bright and luxurious red with gold woven in each seam. She walked a pace behind the Emperor of Xing, close enough to protect him at a moment’s notice, but far away enough as not to disrespect his honor. Glancing around the area, she made sure the other guards were in position as well.

“You can relax a little,” Ling said as they entered the ballroom. Only a few dozen people were already there, milling about in the corners of the room. Grumman nodded at them. “If anyone were to be assassinated today, it would probably be Mustang.”

Lan Fan paused. “Why Mustang?”

Shrugging, Ling responded, “Don’t know, just a feeling.”

Lan Fan continued to stare at him. 

“I’m kidding,” Ling said, hoping to alleviate her worry. “No one is getting assassinated.”

Ling made small talk with an emissary from Aerugo and some of the new generals of Amestris, Lan Fan standing a few paces behind him. And soon, the ballroom began filling up with guests -- an old man, a pretty girl, an angry delegate. 

Fuhrer Grumman approached Ling, nodding at him out of respect. The Emperor and Lan Fan returned the nod in turn. “I am honored that you could attend tonight’s ball. I’m sure your travels left you weary.”

“No more weary than usual,” Ling replied. They began to discuss the upcoming talks, playing a game of influence and control that Lan Fan didn’t fully understand, but then again, it wasn’t her job to understand. And the beginning of their night, along with the expected gossip, swayed to the same tune.

_“Of course, the Ishval Restoration Efforts are going splendidly. General Mustang and Lieutenant Colonel Hawkeye are doing great-”_

_“The proposed anti-war policies might actually be-”_

_“Alphonse Elric? Oh, yes, I’ve heard he’s been in Xing since-”_

_“I expect that we can continue this tomorrow-”_

After another flurry of people, the emperor suddenly turned to his loyal guard. “Lan Fan, I am giving you the rest of the night off. No refusing!” Ling said before she could argue with him. “Go have fun. Talk to someone. Bully Mustang. Eat everything on the banquet table.”

“Emper-”

“No refusing!” Ling stated again. And after a very brief staring contest, Lan Fan reluctantly agreed. She motioned to the other guards, signing the unexpected message, and they signaled back their confirmation. Her unwavering stare screamed, _‘you better pay extra close attention to our Emperor unless you want to die by my hand.’_

Lan Fan walked towards the banquet table, hands tucked in her pockets. She ate until some of the diplomats from Creta started giving her strange looks, and then strolled around the confines of the ballroom, nodding at Riza Hawkeye as she passed her. She tried not to look at Ling and Edward -- who were probably plotting something-- as she made her way back to the banquet table. 

Finally, she made her way to the balcony. Lan Fan had grown tired of her monotonous routine and the chatter of the other guests. She liked to keep to herself. And if she wasn’t on duty, then what was she supposed to do?

Lan Fan shut the glass doors behind her. The balcony was quiet -- peacefully quiet. Even the streets below were void of the humdrum of life, probably due to the wide security perimeter around the building. Lan Fan sighed deeply. Her automail arm was beginning to ache. 

She didn’t know how long she had remained there.

Lan Fan heard the door open. Instantly, she was on edge. 

A voice, soft as the music playing in the ballroom and beautiful as the dress the girl was wearing, spoke up behind her. Her hair was a light blonde with a single curl framing her delicate features and her eyes were the brightest blue Lan Fan had ever seen. “From this view, Central City reminds me of the stars.”

“I suppose,” Lan Fan replied after a moment, hoping the girl didn’t notice her staring. “I don’t pay much attention to the stars.”

The girl’s sweet smile widened. “Perhaps you should make it a new hobby.”

Her dress was a lovely shade of lavender, detailed with lace and beading, and it appeared almost as expensive as Ling’s robes. But what really caught Lan Fan’s attention was her face, the familiarity of soft skin and that blonde curl and _sparkles._ “Have I met you before?”

“No, but you’ve most likely met one of my siblings,” the girl replied. She hid her hands behind her, which were wrapped in gloves made from the finest silk, but Lan Fan could tell she was wringing them. “My name is Catherine Elle Armstrong.”

Just barely, Lan Fan’s eyes widened. 

The Armstrong Family was legendary in Amestris. They had served in the military for generations, growing their wealth, importance, and power; if rumors were true, each member was incredibly strong and gifted in their own right. If there were such a thing as royalty in Amestris, it would have to be the illustrious and noble Armstrong Family. 

Lan Fan nodded her head in respect. “It is a pleasure to meet a member of the Armstrong Family. I am Lan Fan, the head of the Xingese royal guards.”

Catherine nodded slowly at her words. “I traveled there once,” she murmured. “Xing is a beautiful country; my family and I were able to see your exquisite scenery and eat your finest food. We saw the ancient ruins of Xerxes on our way there too -- absolutely stunning.”

“Yes, stunning, Miss Armstrong,” Lan Fan agreed, “and terrifying.” 

Catherine giggled behind her hand -- a sound like morning chimes. “You can call me Catherine. Or- Cath.”

“If you wish, Catherine.”

“Thank you.” The girl moved closer to Lan Fan, leaning against the railing of the balcony. The air, thick with the sweetness of early springtime, swept through Catherine’s hair, the chill dusting her cheeks the softest of pinks. “The flickering lights, those are what remind me of stars. And if I lift my finger, sometimes I can trace the same constellations that I see in the sky.” 

For a few moments, Lan Fan didn’t say anything. The balcony was startlingly quiet; if she paid closer attention, used intuition that she had spent years honing, she could hear the soft hum of ballroom music and the faint chatter of charismatic politicians. Instinctively, Lan Fan glanced through the glass doors of the balcony and Ling was still talking to Edward -- safe. Then there was the girl next her, a beautiful girl in a beautiful dress tracing out the fragments of city lights with her fingers. “If I may ask, what are you doing out here? There must be people at the ball that wish to talk with you.”

Catherine gave Lan Fan a coy look that made her breath catch in her throat. “I’m sure there are.”

“I’m sure you want to ask me a similar question,” Lan Fan said next. She kept her gaze on the streets of Central City, on the haze of lights coming from each home -- they really did look like stars. 

“Are you going to make me say it?”

Lan Fan sighed. Her cheeks felt cold, her automail felt cold. But her chest was so, so warm. “Like I said before, I am head of the Royal Guards of Xing; my duty is to protect my emperor, but tonight he has requested for me to leave my duties to the other guards- to _have fun._ ” 

Her hands were perched on the balcony railings, her fingers dancing across them as though she were playing a melody only she could hear. They were so graceful. “Are you having fun?” Catherine asked. 

“I have a few old friends and acquaintances from my last journey to Amestris,” Lan Fan said, meeting Catherine’s stare. “But most of them seem busy and I think I’ve already visited the banquet table more times than appropriate. And I don’t like _playing the game._ ” 

After a few moments of silence, Catherine reached her hand out. A smile tugged at her reddened lips. “Lan Fan, will you dance with me?”

Lan Fan tensed, her muscles constricting under her suit. She stood stiff as a board and resisted the urge to immediately grab Catherine’s offered hand. “I- what?”

“I didn’t want to come to this ball in the first place,” Catherine confessed. “I have a strong dislike for the politics of these events as well. And now, I’m making it worth my while.”

Lan Fan lifted an eyebrow. “A strong dislike?”

Catherine’s smile was innocent, but there was mirth in her eyes. And when she spoke, it was a shared whisper, a secret between the two of them. “Yeah, I fucking hate politics.” 

Well then.

“My loyalty is to my country and my emperor,” Lan Fan said after a moment. “After tonight, I’m going to return to Xing.”

“I know.”

Then, Lan Fan looked at Catherine -- really looked. Beyond the beauty of her heart-shaped face framed by blonde locks and her slender figure wrapped tightly in an expensive dress. She looked at a girl from the illustrious Armstrong family who traced the stars with her fingers and laughed out of genuine kindness and played the piano on the railings and cursed casually in front of her.

There was something bright in Catherine’s eyes, something enthralling. “I’m simply asking you to dance.”

And when Lan Fan put her hand in Catherine’s, she didn’t so much as flinch from the weight of her automail arm. Catherine tugged at her and motioned for her to follow. As soon as the door opened, the air burst with the cacophonous hum of life. They return back to a world of clinking champagne glasses and laughter that seems obviously fake and smiles that seem even more deceptive. 

Out of the corner of her eyes, Lan Fan could see Ling speaking to General Armstrong. She would have to question him about that later. 

They were bathed in the gold light twinkling off of the chandeliers. Hand in hand, Lan Fan matched Catherine’s pace, matched the sharp click of her heels, and took the lead. She led Catherine’s hands to her shoulders. And she let her own rest on Catherine’s hips. Lan Fan leaned in closer -- Catherine smelled of lavender. In the center of the ballroom, everything else faded around them. 

At the week’s end, Lan Fan knew she would have to return to Xing. And at the night’s end, she knew she might never see Catherine again. 

In that moment, Lan Fan simply wanted more than a dance.


	2. midnight dance

**Notes for the Chapter:**

> guess what i never expected? that's right, chapter two of this fic. spite brought me here xoxo. shout out to my irl, hetchie, for being the best!! and also a huge thanks to arianeige for being my beta and awesome as always. lastly, a huge thanks to yall for reading this!! 
> 
> -jury

In Catherine’s opinion, her parents spent way too much fucking time discussing politics. It was something that entrenched itself in their history, lacing through every part of their foundation till it could do nothing but be passed down the Armstrong line with each generation. But Catherine understood; they were one of the most influential and prominent families in Amestris- a reputation like that came with a price. 

And that was a price Catherine was learning to pay from the moment she was born. Learning how to act in a way that drew people in and speak in a way that her words were the only thing they would remember. Learning grace and poise and dignity and honor.

 _In every action you take, every word you speak,_ her parents would say, _you have to keep the family name in mind._

There was, of course, one exception- Olivier. 

Olivier was stone fucking cold, as sharp as the edge of her rapier, and the most capable woman Catherine had ever met. She lived by her own word, fought with her own spirit, and the opinions of others were as fragile as glass. Olivier didn’t follow much of what their parents taught her, and yet, Catherine still found her older sister to be the most respectable. 

Maybe there were _still_ some hidden politics she hadn’t been considering. 

Nevertheless, Catherine had grown accustomed to thriving in the shadows of her older siblings. Alex was also respectable in his own right, a distinguished man in the military and a State Alchemist at that. And Amue and Strongine had plenty of their own accomplishments under their belts. But even still, Catherine was still a part of the Armstrong family and that meant prospering at representing them. 

That’s how Catherine found herself gracefully walking towards a ball the Amestrian government was hosting before, an event which was meant to proceed a week of diplomatic talks and negotiations between Amestris and many of the surrounding countries. She stayed one step behind Olivier who was decked out in her official military uniform, each award and honor she’d ever received pinned proudly on her coat. 

“Are you ready?” Olivier said, not looking behind her. They were walking up the steps of the building, the wind chilling Catherine through her gown. 

Catherine smiled. “Of course, sister.”

“Good,” she stated, a smirk forming on her face- something Catherine wouldn’t dare call fondness. “Don’t let them eat you alive in there.”

“Of course,” Catherine repeated and then paused as they reached the last step. “I don’t think I would make for a good meal either.”

One last look between the two before they began to make their way inside. 

The two of them had done this before, and at this point, most of their relationship was spoken through glances. The moment they stepped through the threshold of the ballroom, all these goddamn politicians and delegates started flocking towards them, and Olivier took it in stride, Catherine following suit; the Armstrong family had raised good liars with pretty faces. 

“I’m so glad we found the opportunity to meet with one another,” an older man with glasses said. “The Armstrongs’ never disappoint.” 

Catherine nodded softly, a delicate smile on her face. “Yes, of course.”

Another man chimed in. “Catherine, if I could have a moment of your time-”

And the night passed on like that: surrounded by flurries of people vying for her attention, fake words, and even faker fucking smiles. Catherine eventually found herself alone near the balcony; she patted down her lavender dress and took a moment to catch her breath. People were still swarning Olivier, but one last glance from her older sister told her that she could keep her distance. 

She took in the ballroom. Many guests were dancing to a jovial tune, drinks in one hand and their other intertwined with their partners. The higher ups and foreign officials Catherine recognized stuck near the tables and food, socializing and talking amongst themselves. She saw Roy Mustang and Riza Hawkeye sitting near two ambassadors she had met earlier from Creta. Oh, and the Fullmetal Alchemist was there too. 

The music lulled. The chatter deafened. The lights sparkled. 

And Catherine saw a girl on the balcony. 

She recognized the girl in the black suit -- and wow, didn’t she look amazing -- from before. The girl who didn’t bother chatting with anyone, but spent the night walking the perimeters of the ballroom. The melody began to swell and Catherine began her approach. 

And then, everything changed. 

It started with the stars and a feeling she had never felt and suddenly, Catherine found herself whispering _dance with me._

Lan Fan’s hand was heavy in her own and the fabric of her glove felt warm and comforting. Her eyes were a cool black, piercing and alight with the glow of the dangling chandeliers above them. They moved in time with one another and the moment she felt Lan Fan’s hand brush against the small of her back, everything fell into place. 

_Tick. Tock. Tick. Tock._

Catherine recognized the song the live band was playing. It was an upbeat tune that she’d heard countless times at other various balls and events. The song had a pretty melody, made of catchy arpeggios and warm trills. Her mother had once asked her to learn it on the piano. 

“I love this melody,” Catherine said as the tempo rose. “Have you heard it before?”

Lan Fan shook her head, her bangs falling in front of her eyes. “No, I haven’t. Maybe you should be the one leading then, Catherine.”

Cathine giggled without even meaning to. “Don’t worry, I can tell you’re a quick learner.” The hands on Catherine’s waist tightened as they got swept up in the music. It was… freeing being near Lan Fan, allowing this rush to pump through her veins. Lan Fan’s steps were awkward at first, but Catherine could tell there was already a precision to them that only came with practice -- she had a fighter’s body. She did mention she was head of the Xingese Royal Guard, and damn, _wasn’t that something._

As the next song began, another lively tune of strings and harmony, Catherine could feel Lan Fan getting more comfortable with the movements. They pulled each other closer and Catherine could feel the warmth coming from Lan Fan’s body, the burn of dancing the night away. 

“This instrument,” Lan Fan’s voice had lost some of its careful monotony. “It reminds me of something that’s often played in Xing.” 

“I would love to hear about it,” Catherine said in turn. _Tell me everything about you,_ Catherine wanted to say.

And the night began to blur before their eyes. Lan Fan had opened up to her about her country and her emperor and all the adventures they had gone on together. Catherine had told her about all the places she had been and people that she met and family stories her mother might clutch pearls hearing. Whispers of dreams and aspirations were passed between the lull of each note. 

A new song came on, one that Catherine knew as well as the beat of her own heart. “Here,” Catherine whispered, moving her hands from Lan Fan’s shoulders. “Let me take the lead.”

Lan Fan’s eyes widened and she followed without saying a word. It was a dance of threes and Lan Fan quickly learned to keep in time with her; Catherine waited for the music to pick up, a smirk already beginning to form on her face, and she could see Lan Fan looking on in curiosity. 

“Hold on tight, Lan Fan,” Catherine laughed between breaths. 

The song hit its crescendo and Catherine picked Lan Fan up _like it was nothing._ Her dress fluttered at her feet as she twirled Lan Fan around, a smile dancing its way onto her face. When Lan Fan found the ground, they stood there for a moment, their chests heaving and their hands intertwined. And a laugh rose in Lan Fan’s throat, giggly and bursting and everything that Catherine wanted to hear.

Pride swells through Catherine. 

“Can you do that again?” Lan Fan asked, her voice just barely audible against the music. 

And Catherine obliged. 

They continued to dance like this until the music slowed. 

Lan Fan’s hands fell back to her waist as she took lead again. She pulled Catherine tight against her as they swayed in time with one another. Catherine could feel the warmth in her face and the sweat glistening her skin from all that dancing; she liked to think she was fit, but even she needed a moment to catch her breath. She rested her head on Lan Fan’s suit; the fabric was cool and silky and smelled of a scent Catherine was becoming intimately familiar with. 

_Tick. Tock. Tick. Tock._

“I don’t want this moment to end,” Lan Fan murmured, her breath brushing through her hair. 

Catherine leaned back and took Lan Fan in. Her bangs were beginning to stick to her forehead and her cheeks were dotted shades of pink and her nose was crinkled cutely and her eyes were so, so honest. “Me too.”

She brushed Lan Fan’s hair out of her face. “Thank you for dancing with me.”

And as the song ended, she could feel something left unsaid. For a moment, silence reigned upon them, and then the next tune began to play, another jovial one of staccato notes and sharp trills. 

“Let me get you a drink,” Lan Fan said, taking her hand and moving her off the dance floor, careful to steer away from bustling bodies and groups of conversation. 

Catherine smiled. “I could do with one of those. You’re not an easy person to pick up.”

“You don’t have to bother humoring me,” Lan Fan responded. “I-”

Catherine glanced towards where Lan Fan was looking… which was at the Flame Alchemist… whose shirt was dissolving before their very eyes. And the Fullmetal Alchemist and the Emperor of Xing standing right behind him laughing. 

What the absolute fuck. “That seems improper,” Catherine said finally.

Lan Fan looked back at Catherine, letting go of her hand. “Will you excuse me for a moment? I have something- I need to take care of.”

Catherine nodded understandingly. “I’ll get us those drinks.”

 _“My Lord!_ ” She heard Lan Fan yell behind her, and Catherine couldn’t help but giggle into her hand. 

She got two flutes of champagne from a waiter, thanking him with an appreciative nod, and moved to sit down at a table with Olivier and someone she vaguely recognized as Olivier’s colleague. She patted down her dress as she sat down and offered a kind smile. 

A heavy glance passed between them. “You look well,” Olivier said simply. 

“As do you, sister.”

“I’ll have to get you home soon,” Olivier stated, nodding to the clock hanging over the entrance of the ballroom. 

“I understand.”

Olivier’s chair squealed behind her as she got up. Her eyes carried the same confidence they always did. “The party from Xing is a nuisance. It’s a shame we’ll be seeing them frequently in the future.” Olivier began walking away and her colleague followed suit.

Catherine nodded, hiding her smile. “Yes, indeed.” 

Lan Fan began to return to the table, annoyance still in her eyes but a smirk to her lips. She couldn’t find the emperor anywhere in sight- or Roy Mustang for that matter. She was sure Riza Hawkeye, the lieutenant Catherine had heard so much about from Olivier, was taking care of him.

“I took care of it,” Lan Fan said, taking the seat where Olivier once was.

Catherine handed her a flute. “I’m sure you did.” 

Lan Fan accepted it gratefully. And the rest of the night passed in a haze of fond gazes and shared secrets and fingers interlocked. The event began to die down as politicians and officials left to prepare for the upcoming talks. The band began to slow, and the lights followed as they dimmed. And as the clock carried on and Olivier began to usher her out of the ballroom.

Catherine rushed up to hug Lan Fan, throwing her hands around her shoulders and her head against the crook of her neck. Their hearts beated against each other. 

_Tick. Tock. Tick. Tock-_

A countdown began.

Catherine leaned in close, her breath hot against her ear and her voice like honey. “The next time I vacation in Xing, I want you to dance with me again.”

“And the next time we dance together, I’ll be the one picking you up.” Lan Fan’s tone was heavy with promise. “And Cath, the next time we meet, I’ll tell you about the stars.”

**Notes for the Chapter:**

> cheers to completing the first cathlan fic! thank you all so much for reading, any and all comments, kudos, and bookmarks are appreciated!! i hope you all have a wonderful day.
> 
> -jury


End file.
